Plastic surgeons, dermatologists and their patients continually search for new and improved methods for treating the effects of an aging skin. One common procedure for rejuvenating the appearance of aged or photodamaged skin is laser skin resurfacing using a carbon dioxide laser. The carbon dioxide laser energy is absorbed by tissue water causing vaporization of the outer skin layer. Carbon dioxide lasers have been utilized for approximately three decades. However it has only been the past few years that these lasers have been arranged to remove only thin tissue layers with minimal heat damage to the surrounding skin. While carbon dioxide lasers may remove about 150 microns of skin, that skin may take a month or more to heal under such a procedure.
Er:YAG lasers have been utilized to ablate even thinner layers of tissue than carbon dioxide layers. However they lack the coagulation characteristics and thus allow more bleeding than a carbon dioxide laser during use.
Non-ablative skin rejuvenation is a methodology which does not take the top layer of skin off, but which uses a deep-penetrating laser to treat the layers of skin beneath the outer epidermal layer, treating unsightly vascular and pigmented lesions, and shrinking and modifying the underlying collagen, tightening the skin and reducing wrinkles to provide a more youthful appearance. This methodology however, has a low efficiency, and an aggressive cooling method must be used on to the skin so as to minimize damaging the top or upper layer thereof and also to minimize pain generation. The “fluence” or energy density used is greater than 10 joules per square centimeter and to be more effective this fluence often reaches 30 Joules per square centimeter. This level of energy often causes pain and epidermal damage.
U.S. Published Patent Application No. 2002/0161357 A1, by Anderson et al, discusses a method and apparatus for performing therapeutic treatment on a patient's skin by using focused radiation beams to create “islands” of treatment/damage within untreated portions of the patient's skin. However, the parameters of the treatment beam in this method are not optimal for skin rejuvenation treatment.
Yet another treatment method is disclosed in U.S. Pat. No. 6,077,294 to Cho et al., the entire teachings of which are incorporated herein by reference. This patent describes a system and methodology for noninvasive skin treatment that utilizes a pulsed dye laser having a wavelength of about 585 nanometers (nm), and an energy of less than 5 Joules per square cm. In contrast to earlier techniques which used higher-energy pulses to damage and “shrink” the collagen below the epidermis, the relatively lower energies of the beams in the '294 patent are designed to stimulate the collagen to regenerate and “fill in” valleys of the skin for a younger more clearer skin.